Coating composition and film produced thereby



Patented Mar. 15,1932

1 UNITED STATES.

PATENT orr cn WILLIAM HEN BY MOSS, OF CUMBERLAND, MARYLAND, ASSIGNOB TO GELANESIE' COB- PORATION OF AMERICA, Av CORPORATION OF DELAWARE con'r'nw oomrosrrron m rrLm: rnonucrm my m Drawing. Original application med May 12, 1928, serial in. 277,393. Divided and this application filed July 16, 1929;

This invention relates to coating compositions containing derivatives of cellulose and particularly to a new and improved synthetic resin for use in the same prepared from lactic 5 acid. 1 This application is a division of my prior application No. 27 7,393 filed May 12, 1928.

n object of my invention is toprov'ide a coating composition containing derivatives of cellulose, and particularly organic substitution derivatives of cellulose, that produces clear, homogeneous, hard, tough and light fast films.

A further objectof my invention is to provide :a suitable resin for lacquers containing organic substitution products of cellulose, such as cellulose acetate, which resin is com-- patible with the other constituents of the lacquers andwhich produces clear solutions which, upon drying, form films that are adherent, tough, hard and lightfast.

The preparation of a lacquer containing organic derivatives of cellulose, such as cellulose acetate, as the main constituent of the lacquer base, which lacquer is to be applied to a hard, smooth surface, presents many difficulties. This is due primarily to the fact. that films from lacquers containing cellulose acetate as the sole constituent of the lacquer base do not adhere to smooth surfaces. When attempts are made to incorporate natural gums or resins in the lacquer, containing cellulose acetate in order to impart the necessary adhesive qualities to the films roduced fromit, both the lacquer and the lms produced become cloudy and unhomogeneous. a

I have found that the synthetic resins produced by the heating lactic acid are compatible with'cellulo'se acetate, and that when added to lacquers containing cellulose acetate, they form clear solutions that, upon drying, produce clear, hard, tough and firmly adherent films, which, in the-undyed orunpig- ,mented form, are almost colorless and fast to light. a

The selection of a suitable resin for a lacquer containing the organib derivatives of cellulose presents a difiicult problem becausethe resin must be compatible with the organic .50 derivative such as cellulose acetate, both in Serial No. 378,814;

solution and in the 'dry films, and also with softeners, pigments and dyes which may be used to roduce desired eifects and variations of the lms. In general, a synthetic resin for this purpose would be easily prepared from preferably cheap materals; it should,

of itself, be practically neutral and should not easily discolo'r'when exposed to light and beffree from water soluble materials. It should be hard and solid at ordinary temperatures, and its solutions from volatile solvents should dry quickly and completely when applied as a film without a long continued retention of low boiling point solvents.

I- have found that the synthetic resin obtained by heating lactic acid is entirely compatible with the said cellulose derivatives,

such as cellulose acetate, and that it can be added to lacquers so that there are produced therefrom clear, hard, films possessing the additional useful property of sticking to metal, wood, fabric, glass, etc., which is not inherent in the cellulose derivative itself.

I have also found that this resin ,canbe added to cellulose derivatives when, used in plastic masses and films, wherever the addition of'a resin is desirable or advantageous.

used the following are given by way of example diethyl phthalate, tricresyl phosphate, triphenyl phosphate, methyl toluene sulphonamide, triacetin, phenylol propane, thiocarbanilid, etc.

Examples of medium and/orh1gh boiling amides such as mono solvents are ethyl acetate, ethyl lactate, tetra- V chlorethane, benzyl alcohol or 'diacetone alcohol. Obviously other-suitable medium or other organic solvents and is entirely misci- 'ble with cellulose acetate in solution and in high boiling solvents may be used, The low boiling solvents may be any one or a mixture'of two or more of any of the following liquids: acetone, alcohol, (ethyl or methyl) benzene or ethylene dichloride. The pigments or dyes used may be any of the pigments or dyes ordinarily used in the paint or lacquer industry that are suitable for the purpose.

The following is an example of preparing the lactic acid resin. -The resin is prepared from lactic acid preferably 90%- CH CHOHCOOH, by heating it under reflux for several hours, and then distilling.

ofit the volatile portion. The heating and distillation may be done either under pressure or-under vacuum and also at atmosphericv pressure. The light yellow resin has a meltingpoint about 3035 C. and is a mixture of lactide CH CH.O.CO.CO.O.CHCH and lactyl lactyl lactic acid: CH CH(OH)CO.O.CH(CH3) CO.O.CH(CH3)COOH and other dehydrated and polymerized forms of lactic acid.

The resin is soluble'in acetone, alcohol and films. It is compatible with the usual high boiling point solvents and plasticizers or softeners also commonly used in cellulose acetate lacquers, and the lacquers produced by addition of this resin on application to metal,

wood, etc., are clear, hard, well-stuck.

The resin may be dissolved alone in any suitable solvent or mixture of solvents. and

the solution thus produced may be added to a solution of cellulose derivative in the 'same or other solvents and plasticizers, dyes, pigments, stabilizers, may be added to either 01' both solutions or to the mixed solution, or the resin and the cellulose derivative may be dissolved together in the desired solvents or mixture of solvents or mixture of substances which are themselves non-solvents for cellulose acetate and resin, but which become solvents when mixed to ther, and dyes, pigments and plasticizers, may be added as desired, at any state in the aboveproceedings.

Further. I have .found that the above resin is especially desirable for admixture with other synthetic resins, the said mixtures of resins being also compatible with cellulose acetate in solutions, lacquers, plastic masses and films.

Thus also the lactic acid resin may be mixed with natural resins such as kauri, Pontianak, manila, dammar, rosin and semiartificial resins such as ester gum, all of which mixtures are compatible with cellulose acetate in solutions, lacquers, films, plastic masses, al-' though the-said natural resins and ester gum are not of themselves compatible with cellulose acetate.

skilled in the art.

Ewample I Parts Cellulose acetate 10 Lactic acid'resin 10" are dissolved in 100 parts of a solvent. This solvent may be acetone alone or a mixture of acetone or other volatile solvents.

Ewample l A coating composition may be made up of the following composition:

Parts Cellulose acetate 15 Lactic acid resin 5 Acetone 50v Alcohol 25 Benzene 25 Ewample I I I The following is an example of a coating composition containing the synthetic resin and also containing softening agents, pi ments and medium and/or high boiling so vents.

Parts Cellulose acetate 25 Lactic acid resin 10 -Pigments A 10 Diethyl. phthalate 5 Acetone c 50 Ethyl acetate 20 Toluene 10 Diacetone alcohol 10 It is to be understood that the-foregoing details are given merely by way of illustration and'that many variations may be made therein without departing from the spirit of this invention.

. Having described my invention, what I claim and desire to secure by Letters Patent 1. A composition of matter containing a derivative of cellulose, a synthetic resin formed by the condensation of lactic acid.

- 2. A composition of matter containing an organic derivative of cellulose, a synthetic resiin formed by the condensation of lactic a'ci 3. A composition of matter containing cellulose acetate, a synthetic resin formed by; the condensation of lactic acid.

4. A coating composition contain' a derivative of cellulose, a resin formed y the condensation of lactic acid and volatile solvent therefor. 4

5. A coating composition containing an organic derivative of cellulose, a resin formed by the condensation of lactic acid and volatile solvent therefor.

6. A coating composition containing cellulose acetate a resin formed by the condensagion of lactic acid and volatile solvent thereor. v 7. A coating composition containing a cel I lulose acetate, a plastifier, a resin formed by the condensation of lactic acid and a volatile solvent.

8. A coating composition containing a cellulose acetate, a plastifier, a synthetic resin, a resin formed by the condensation of lactic acid, and a volatile solvent.

In testimony whereof, I have hereunto subscribed my name.

WILLIAM HENRY MOSS. 

